Draindown solar hot water systems work as a kind of "solar add-on" to a grid-tied hot water setup. They consist of a collector array, a tank and piping which connects to the normal household plumbing, plus optional controllers, valves and gauges.
It may seem a novel concept to heat your domestic water supply with a refrigerant, but it's not so odd when you really think about it. After all, the area behind the refrigerator in the kitchen is pretty warm, so surely there's a way to turn this to your advantage?
In most parts of the world, space heating systems are installed in every home. They provide warmth and comfort during the colder part of the year. Unfortunately, the vast majority of these systems rely on grid-tied, non-renewable power sources to provide that heat. In a bid to reduce our environmental impact – not to mention our operating costs – we can use the sun's power to provide space heating.
Before you decide which kind of system you're going to install, it's important to understand the basic terms used to describe them.
An open loop or direct system is the simplest: the domestic water actually enters the solar collectors and is heated by them before heading back to the storage tank.
Like solar thermal hot water installations, there are many different options available for space heating. Before you consider them and work out which is best for you, it is important to be aware of the limitations and pre-installation suggestions outlined below.
A pressurized system should really be referred to as a "closed-loop pressurized antifreeze solar thermal system" – the two-word version is much simpler and more common! Pressurized systems are the most flexible type of solar hot water installation and, consequently, are the most common worldwide.
A pressurized solar hot water system almost always follows a standard layout, which is one of the reasons most manufacturers are able to offer simplified kits for residential installations.
[If you haven't read Part 1 of this article, you should!]
